Text Models and Markup

Prof. AlvaradoMDST 3703

17 September 2013

Business

• Plan B: If Home Directory is not working for you, please use the Hive – Go to http://its.virginia.edu/hive/connected.html – Install VMWare Client– Use Notepad++ – Home Directory link your Desktop (also as J drive)

• Tutorials– If you feel lost about HTML let me know

Review 1: Textual Signals

• Each of the authors last week viewed the text as a kind of signal

• A signal is a pattern that contains messages• Messages can be grasped through parsing the

signal• What were the messages? How were they

parsed?

A text can be viewed as a long signal consisting of characters selected from a common set of characters

A model of communication.Messages get converted into signals and back into messages

by means of a shared code.

ENCODING DECODING

SHARED CODE

Person 1 Person 2

Author Parsed elements Decoded message

Levi-Strauss Relations and bundles

Structural oppositions

Colby Thesaurus words Thematic patterns

Ramsay Scenes Genres

Text is like this. This is a map of DC generated by thousands of individual Flickr and Twitter events.

The picture is a kind of signal—collective and unconscious, yet meaningful.

The patterns discerned from the signals are not intentional, but they are the products of intentional activity.

http://anthonyflo.tumblr.com/post/7590868323/photographer-and-self-described-geek-of-maps

[Text is like this]

Review 2: Semantic HTML

• Also called POSH—”Plain Old Semantic HTML”• The use of HTML to describe a text, not to

format it (CSS is used to format)• DIV, SPAN, CLASS, and ID are general purpose

tools to provide more flexible markup• What kinds of things can POSH be used to

describe?

SegueSemantic markup may be used to support the analysis of each of our authors—including

AristotleAristotle: Elements of drama, Elements of plot

<div class=“plot-element” id=“reversal-of-fortune”> ... </div>

Levi-Strauss: Relations and Bundles in myths<span class=“relation”> ... </span>

Colby: Theme words in folktales<span class=“antagonism”>fight</span>

Ramsay: Scenes in plays<div class=“scene”> ... </div>

Let’s step back and look more closely at “text”

Let’s look at some material examples

page o’ text

Real world text comes packaged in documents

How is text conveyed in a document?

A document is a material artifact—a medium with which to convey a signal

What is text?

Visual Signifiers

• Small caps• Indentation• Alignment• Italics• Space

All used to signify elements of text

Other examples

[Charrette]

[The Wasteland]

[Critical Edition]

[OED]

Documents have thee Levels: Structure, Content, Style

StructureThe organization of content into units (elements) and logical relationships (e.g. reading order)

ContentTEXT, images, video clips, etc.

StyleScreen and print layoutFonts, colors, etc.

Descriptive markup languages allow us to define structure of documents for

computational purposes

Theoretically, they do not specify layout or content

[PDF, Procedural Markup]

In contrast to procedural markup like PDF

So, how are documents structured?

Hierarchically …

(theoretically)

Document Elements and StructuresPlay– Act +

• Scene +– Line +

Book– Chapter +

• Verse +

Letter

– Heading• Return Address• Date• Recipient Info

– Name– Title– Address

– Content• Salutation• Paragraph +• Closing

These are all “trees”

XML is a markup language

It is a more powerful system for semantic markup than POSH

What is XML?

• Stands for eXtensible Markup Language– Actually invented after the web– A simplification of SGML, the language used to create HTML– It specifies a set of rules for creating specialized markup

languages such as HTML and TEI• It is simplified version of the SGML

– Standard Generalized Markup Language• SGML was invented in the early 1970s to wrest the

control of documents from computer people who were taking over industries like law and accounting

XML looks like this

Notice how the element names reference units, not layout or style

Also markup for “in-line” elements

XML Premises

1. All documents are comprised of elements.2. Elements contain content.3. Elements have no layout.4. Elements are hierarchically ordered.5. Elements are to be indicated by “markup” –

tags that define the beginning and end of an element

XML Markup Rules

• Tags signify structural elements• Three kinds of tag– Start and End, e.g <p> and </p>– Singleton, e.g <br />

• Start and singleton tags can have attributes– Simple key/value pairs– <div class="stanza" style="color:red;">

• Basic rules– All attributes must be quoted– All tags must nest (no overlaps!)

Documents in XML that meet these rules are “well formed”

XML also provides Document Types• A Document Type Definition (DTD) defines a set of tags

and rules for using them– Specifies elements, attributes, and possible combinations– E.g. in HTML, the ol and ul elements must contain li

elements• A DTD is just one kind of schema system used by XML • Schema express data models of/for texts– TEI is a powerful way of describing primary source

materials for scholars• Documents that use a schema properly are called

“valid”

Originally, DTDs defined “genres” like business letter or mortgage form

They were later used to define more abstract models of textual content

XML is used everywhere

• HTML– E.g. Embed codes

• TEI (Text Encoding Initiative)• RSS• Civilization IV• Playlists (e.g. XSPF or “spiff”)• Google Maps (KML)

The Text Encoding Initiative created TEI to mark up scholarly documents

Mainly primary sources such as books and manuscripts

TEI

• Written in XML (was SGML)• The dominant language used to encode

scholarly text• Scholars can select from a large set of

elements or their own elements to match what they are interested in

Examples

• The TEI Header– http://tbe.kantl.be/TBE/examples/TBED02v00.

htm• TEI Prose– http://tbe.kantl.be/TBE/examples/TBED03v00.

htm • Find others at the TEI By Example Project– http://tbe.kantl.be/TBE/

XML and TEI both contain an implicit theory of text

What is it?

OCHO

• XML (and therefore HTML and TEI) imply a certain theory of text– A text is an OHCO

• OHCO– Ordered Hierarchy of Content Objects

• An OHCO is a kind of tree– Elements follow each other in sequences– Elements can contain other elements

What are the advantages of this view?

OHCO allows for easy processing

• Every element has a precise address in the text– E.g. HTML/body/p[1]

• Texts can be described in the language of kinship– Ancestors, parents, siblings, children, etc.

• Texts can be restructured and manipulated by known patterns and algorithms– Traversing– Pruning– Cross-referencing

What are the disadvantages of OCHO?

Logical vs. Physical Structure

THIS IS WHAT WE ENCOUNTERED AT THE END OF LAST WEEK’S STUDIO

Two common structures that overlap

Pages and Paragraphs

<page n=“2”>. . .<p id=“foo”>His good looks and his rank had one fair claim on his attachment, since to them he must have owed a wife</p> </page><page n=“3”><p id=“bar” prev_id=“foo”> a very superior character to anything deserved by his own.</p>. . .</page>

Solution 1: Split Elements

<p>His good looks and his rank had one fair claim on his attachment, since to them he must have owed a wife <pb n=“3” /> a very superior character to anything deserved by his own.</p>

Solution 2: Use “Milestones”

One structure gets backgrounded

Wittgenstein’s Manuscripts

What about this?

The problem of overlap suggests that OHCO is not a simple as it looks

How does Renear “solve” the problem?

Each OHCO markup schema represents an analytical perspective,

an interpretive model

[Charrette]

So, XML, TEI, POSH – these allow us to impose a model on a text

How does Unsworth characterize these models?

A markup schema is a “knowledge represention”

A KR is a model that comprises

1. A set of categories (aka Ontology)Names and relationships between names

2. A set of inference rules (aka Logic)A method of traversing names and relations

3. A medium for computationA medium for mechanically producing inferences

4. A language for expressing these thingsSuch as a programming or markup language

What tools beside XML does Unsworth reference as useful for KR?

Tables

What are some differences between trees and tables?

Tables are more rigidTrees allow for indefinite depth

But tables are easier to manipulate

In any case, tables and trees are two major kinds of data structure that you will encounter …

How to reconcile these tools?

A Proposed Model

• Texts are not documents– Documents are media, Texts are messages

• Texts and documents are part of a system comprised of “levels”– They are effectively archaeology sites with stratigraphic

layers– Erasures are like cities building on top of each other

• Each level of the system is described by an appropriate set of tools– Document structures XML– Textual structures, embedded ontologies Tables

Basic Levels

• Document– Physical objects (paper)– Logical objects (defined by space, style, punctuation, etc.)– Style and layout (also defined by space, color, etc.)– Can have superimposed versions

• Text– Sequences of characters– Grammatical features– Figures and poetic features– Etc.